Can someone explain the difference between the use of the $_SERVER as script name and this one for host name?

Question

Also there's a lot of main elements that can be used that confuses me on how this are used on the actual code. Like, can someone give a scenario or an example each? Thank you.

Answer 1

script name: the name of your PHP file which you are currently running. For example you have php file called test.php which has following code:
<?php
echo '$_SERVER ["SCRIPT_NAME"]';
?>
it will return test.php....which is the name of currently runninh php file or script.
But host name is different. Remember when u setup simple server in ur machine we call it localhost. and if ur using hosting companies like Hostgator.com, they have their own server name which here called as host name....

Answer 2

$_SERVER is a superglobal variable on PHP. Here on this link, you can find all the uses for the variable:
http://php.net/reserved.variables.server
Hope it helps to you.